1. Field of the Invention
The invention relates to operator/cartridge assemblies generally, and particularly to a latching interface for assembling a contact cartridge or other type of cartridge to a switch operator or other operator.
2. Discussion of the Prior Art
Contact cartridges for use in manually operated pushbutton switches and other electrical circuit operating elements are well known. These cartridges are typically generally parallelepiped shaped and house a set of normally open or normally closed electrical contacts. A spring biased follower carries an electrically conductive contact bridging element and extends outside of the housing of the cartridge. Depressing the follower either opens the electrical circuit made by the contacts, in a normally closed contact cartridge, or closes the circuit, in a normally open contact cartridge.
One or more of these contact cartridges is usually assembled to a manually operated switch or other operator (e.g., a solenoid) so as to allow convenient operation of the follower. It is often desirable to provide as many contact cartridges as possible on these operators so as to operate several electrical circuits with each operator. However, space limitations have generally made only two or three cartridges possible.
It is also desirable to make these cartridges as easy as possible to assemble to their operators. The cartridges are often purchased separately and assembled to their operators under maintenance or "in service" conditions in the field. The portion of the operator that mounts the cartridges typically resides behind an operating panel, and can be inaccessible and in very close quarters, making it difficult to assemble the cartridge to the operator. Also, the interface between the cartridge and the operator should be exclusive, i.e., such that the cartridge can only be assembled to the operator in the proper orientation and positively and securely locked into place.
It is typical to use a snap action locking interface between the cartridge and the operator. In one known construction, a lip of the cartridge is hooked under a ledge of a latch on the operator and the cartridge is pivoted toward the latch until a ledge of the cartridge on the opposite side from the lip snaps under an arm of the latch. In another known construction, a contact cartridge is guided by the latch along a translatory path until biased arms at the ends of the cartridge snap into recesses formed by the latch. In these constructions, if there is insufficient clearance or accessibility to rock the cartridge into place in the formerly mentioned design, or to translate the cartridge into place in the latter design, assembly can be very difficult.
In known switch assemblies having only two or three contact cartridges, the cartridges have typically been made with a transversely symmetrical latching interface and/or follower, and any cartridge could be placed in any position. However, when four cartridges are provided in a single switch assembly, a special problem arises so that following the prior art design of a transversely symmetrical interface and/or follower results in the switches being specialized for particular positions. This in turn would result in an excessive number of different parts, and corresponding problems in ordering, supply, and inventory control, and increased tooling and other capital costs to manufacture the cartridges.